Examples of Bevel Gear Surface Strength Calculations0 pages

17.4.3.L Tooth Flank Load Distribution Factor, KHb
Factors are listed in Tables 17-25 and 17-26. If the gear and
pinion are unhardened, the factors are to be reduced to 90% of the
values in the table.
Table 17-25 Tooth Flank Load Distribution Factor for Spiral
Bevel Gears, Zerol Bevel Gears and Straight Bevel Gears
with Crownina. KHb
Stiffness of
Shaft, Gear
Box, etc.
Both Gears
Supported On
Two Sides
One Gear
Supported on
One End
Both Gears
Supported on
One End
Very Stiff 1.3 1.5 1.7
Average 1.6 1.85 2.1
Somewhat
Weak 1.75 2.1 2.5
Table 17-26 Tooth Flank Load Distribution Factor for
Straight Bevel Gear without Crownina. KHb
Stiffness of
Shaft, Gear
Box, etc.
Both Gears
Supported On
Two Sides
One Gear
Supported on
One End
Both Gears
Supported on
One End
Very Stiff 1.3 1.5 1.7
Average 1.85 2.1 2.6
somewhat Weak 2.8 3.3 3.8
17.4.3.M Dynamic Load Factor, Kv
The dynamic load factor can be obtained from Table 17-24.
17.4.3.N Overload Factor, KO
The overload factor can be computed by Equation 17-11 or
found in Table 17-4.
17.4.3.O Reliability Factor, CR
The general practice is to assume CR to be at least 1.15.
17.4.3.P Allowable Hertz Stress, sHlim
The values of allowable Hertz stress are given in Tables
17-12 through 17-16.
17.4.4 Examples of Bevel Gear Surface Strength
Calculation
Tables 17-26A and 17-26B give the calculations of
surface strength factors of Gleason straight bevel gears.
Table 17-26A Gleason Straight Bevel Gear Design Details
No. Item Symbol Unit Pinion Gear
1 Shaft Angle S degree 90º
2 Module m mm 2
3 Pressure Angle a degree
20º
4 Central Spiral Angle bm 0º
5 Number of Teeth z 20 40
6 Pitch Circle Diameter d mm 40.000 80.000
7 Pitch Cone Angle d degree 26.565.5º 63.43495º
8 Cone Distance Re
mm
44.721
9 Tooth Width b 15
10 Central Pitch Circle Diameter dm 33.292 66.584
11 Precision Grade
JIS 3 JIS 3
12 Manufacturing Method Gleason No. 104
13 Surface Roughness 12.5 mm 12.5 mm
14 Revolutions per Minute n rpm 1500 750
15 Linear Speed v m/s 3.142
16 Direction of Load Unidirectional
17 Duty Cycle cycle Over 107 cycles
18 Material
SCM 415
19 Heat Treatment Carburized
20 Surface Hardness HV 600 ... 640
21 Core Hardness HB 260 ... 280
22 Effective Carburized Depth mm 0.3 ... 0.5
418